Continuous impregnation of formed fibrous material



May 15, 1951 D. D. ADAMS Er AL CONTINUOUS IMPREGNATION OF' FORMED FIBROS MTRIAL Filed July 18, 1946 3 Sheets-Sheet 1 INVENTORS Do uglas 0. dam BY Karl Rollins QV .mmm a D. D. ADAMS ET AL CONTINUOUS IMPREGNATION OF FORMED FIBROUS MATERIAL May 15, 1951 Flled July 18, 1946 May 15, 1951 D. D ADAMs ET AL 2,552,612

CONTINUOUS IMPREGNATION OFFORMED FIBROUS MATERIAL Filed July 18, 1946 S Sheets-Sheet 3 54 INVENToRs Douglas Zlfdams BY fa/1i Hollz'uw Jaim D. Bisher# atented lVay 15,A

CONTINUOUS IMPREGNATION OF FORMED FIBROUS MATERIAL Douglas l). Adams, Karl Rollius, and John D.

Risher, Canton, Ohio, assignors, by mesne assignments, of 76.89 per cent to R. E. MacKenzie and 23.11 per cent to L. V. Bockius Application July 1S, 1946, Serial No. 684,462

2 Claims. l

The invention relates generally to a novel method for continuously impregnating articles `of fibrous material with a chemical compound, in order to strengthen and stiden the articles.

More particularly, the invention relates to a novel method for continuously impregnating articles of preferably laminated corrugated paper board, formed in a particular contour, so as to provide an impregnated article having maximum strength and minimum weight while maintaining its preformed shape.

In impregnating articles of laminated corrugated paper board with a stiifening and strengthening compound, the articles are dipped into a suitable chemical compound, preferably a molten bath of sulfur compound, which on Asolidiiication imparts added strength and rigidity.

We have discovered that in dipping such articles of preformed shape, the articles must be securely bound or held in shape throughout the immersion period, because otherwise the molten bath will cause the article to lose its shape entirely.

We have discovered also that such preformed articles should be dipped in a position which will insure the flow of the molten compound into and through all of the corrugations, because otherwise the impregnation is not uniform throughout the article, and blisters are very apt to form between the plies or laminations in the areas where the compound has not penetrated.

We have discovered further that such preformed laminated articles should be withdrawn gradually from the molten bath in such posiltion as to uniformly and completely drain excess `compound from the articles, because otherwise the excess compound when solidied adds unnecessary weight to the articles, and the excess solidied compound will dust off when the article is used.

We have discovered still further that such laminated articles should be preheated before dipping to drive out moisture in the paper plies, should be immersed under time and temperature conditions which are carefully controlled in relation to the character and dimension of the article, and should be gradually cooled after withdrawing from the bath to insure proper drainage and uniform solidii'lcation of the compound.

The present invention resides in carrying out all of these requirements as part of an efficient and inexpensive continuous procedure, by which preformed laminated fibrous articles are impregnated rapidly to impart maximum strength and rigidity while maintaining their preformed contours and dimensions.

Accordingly, it is an object of the present invention to provide a novel method for continuously impregnating formed laminated fibrous articles to impart strength and rigidity thereto.

Another object is to provide a novel method of continuously impregnating formed laminated brous articles in such manner as to maintain their predetermined shape and dimension.

A further object is to provide a novel method of continuously uniformly impregnating formed laminated fibrous articles and completely draining excess impregnating compound therefrom.

Another object is to provide a novel method of continuously impregnating formed laminated fibrous articles including controlled preheating, dipping and cooling operations.

Finally, it is an object of the present invention to provide an efficient method which will accomplish all of the foregoing objectives so as to produce impregnated laminated fibrous articles of predetermined form and shape on a continuous low-cost basis.

These and other objects are accomplished by the methods which comprise the present invention, the nature of which is set forth in the following general statements, and a preferred embodiment of which is set forth in the following description and illustrated in the accompanying drawings, and which is particularly and distinctly pointed out and set forth in the appended claims forming part hereof.

In general terms, the novel method comprising the present invention includes binding the preformed laminated fibrous articles in shapeholding frames and moving said frames continuously through preheating, impregnating, and cooling zones while controlling the time and temperature in said sones, said articles being passed through the impregnating bath in one position and being inverted as they are gradually withdrawn from the bath.

Referring to the drawings in which a preferred embodiment of apparatus for carrying out the invention is shown by way of example,

Figures la and 1b taken together comprise a diagrammatic plan view of the apparatus with parts in section;

Figures 2U, and 2b` taken together comprise a diagrammatic side elevation thereof, parts being broken away and in section;

Fig. 3 is an enlarged side elevation showing one of the dipping frames for holding one of the preformed articles carried on the endless conveyor which passes over the impregnating tank;V

and

Fig. ,4 is a fragmentary end elevational view taken at right angles to the view of Fig. 3.

Similar numerals refer to similar parts throughout the several views of the drawings.

The laminated preformed corrugated paper articles which are to be impregnated according to the novel continuous method comprising the present invention, are preformed in such contours and dimensions as to provide structural load-bearing units when impregnated. For example, such articles having a channel or multiple channel cross section have been found to be very satisfactory as material carrying platforms used with power lift trucks, and such articles having a'channel or angular cross section have been found to be very satisfactory and desirable when used as structural panels or units incorporated in the walls, floors, ceilings, etc.,` of buildings.

Other uses of such articles will be apparent, and we do not wish to limit this invention to any particular shape or configuration of the articles which are impregnated according to the present invention, except that all of the articles necessarily have one or more angular flanges or legs. The articles shown by way of examples in the drawings as being impregnated are 1naterial carrying platforms or pallets, and as best shown in Fig. 3, they are of a composite channel cross sectional shape having a platform or deck with the corrugations running transversely thereof and six flanges or legs extending at right angles therefrom, with the legs bent across the corrugations so that the open'ends of the corrugations are at the outer ends of the legs.

As best shown in Figs. la and lo and Figs. 2a and 2b, the apparatus includes an elongated tank iii for containing molten impregnating cornpound, and having a preferably sloping entrance end ll and a preferably sloping exit end l2. The tank is filled to a desired level with molten sulfur compound, and the compound may be maintained at a temperature of preferably 130 of an introer such as Thiokol or Aroclor or I-lalowax, ora combination of twoV or more of said introers. Thiokol is a combination of organic polysulfides, Aroclor is a chlorinated diphenyly and Halowax is a chlorinated naphthaiene. However, the impregnating' compound may be varied considerably and the particular composition of the 'compound per se forms no part of the present invention.'

The conveying means for moving the particular articles shown to be impregnated through the molten compound in tank Il) preferably includes a roller conveyor chain passing longitudinally over the center of the tank I, being rollably supported in a tubular track i3 having a longitudinal slot in its bottom wall through which links lll depend for attachment to the carriers which support the dipping frames containin the preformed articles'to be impregnated. The conveyor chain and track are of usual and well known construction, and are therefore not shown in detail in the drawing, and the depending links is carried by the chain are best shown in Fig. 3.

The dipping frames indicated generally at l5 are each adapted to bind and hold inv shape one of the articles I 5 to be impregnated, and the frames are supported by the links lll at intere vals along the conveyor chain rolling in track 3. As shown in Figs. 1a and 1b, after the track i3 passes over the tank it, it'turns to the right 45, then 95 and then 135 to provide a reverse bend il of the track which is connected to a return run IS. The return run i3 of the track is connected at its forward end to another reverse bend i9 similar to the bend il, and which joins the forward run I3 of the track and forms a closed loop.V

As indicated diagrammatically in Figs. 1a and 1b and Figs. 24a and 2b, the track may be suitably supported on the bottom chords C of roof trusses located above the track.

As shown in Figs. 1a, lo, 2a and 2b, a hood 2] is provided over the mpregnating tank lli; and the hood is connected at the exit end l2 of the to a rectangular duct 2i which substantially follows the track around the reverse bend i3 and back along the return run of the track a considerable distance as indicated at 22, sow that the track and dipping frames carried thereby are enclosed by the duct for a substantial period of time after passing beyond the impregnating tank lf2.r The combined length of the portions 2i and 22 of the duct is such as to enclose the dipping frames for several minutes after they are withdrawn from the impregnating bath, and as shown in Fig. 2o, the hood 2G is inclined upwardly at 23 to connect to the duct 20 so that the heated atmosphere under the hood communicates rwith the duct and envelopes the` articles leaving the impregnating tank so that they cool very gradually.

As indicated in Figs. 1a and 2a, the hood 2l] slopes upwardly at the entrance end of the tank to form a portion 24 which merges into and communicates with an L-shaped entrance duct 25 enclosing the reverse bend I9 of the track andthe dipping frames carried thereby, the entrance duct 25 having a portion 25 enclosing the forward end of the return run I8 of the track andthe frames carried thereby. The entrance duct 2,5'is lled with the heated atmosphere within the hood, so

as to provide a preheating zone for the articles entering the duct on their way to the impregnating tank IB. As indicated in Figs. 2.a and 2b the track i3 is inclined parallel with the portions 24 and 23 of the hood so as to pass the articles carried in the frames through the impregnating bath, and the return run I8 of the track is slightly lowered by the downwardly inclined portions '21 and 28 so as to bring the dipping frames/on the return run It of the track to a convenient loading and unloading elevation between the discharge duct 22 and the entrance duct 2-5.

Referring to Fig. 3, the dipping frames l5 are supported on the conveyor chain at suitable in tervals along the same, and the supporting means preferably includes yokes @suitably connected to the lower ends of adjacent pairs of the links |11. Studs 3l are journaled in and extend vertically through the yokes 3D, and longitudinal supporting links 32 are pivotally connected at their ends to the depending ends of adjacentA studs 3l, asA by bolts 33. A cross rod 3c is secured as by l welding to the center of each link at its lower edge, and projects laterally therefrom in each direction so that its outer ends are substantially overV the laterally outer edges of the dipping frame l 5 carried thereby.

The outer ends of the rods 34 have collars 35 swiveled thereon, and the collars are secured as by welding to the upper ends of hanger tubesvd,

, ing through the center thereof.

The hanger tubes 36 telescope over the upper portions of the hanger rods 31, and are ,secured thereto preferably by pins 38 passing through holes in the rods 31. A series of such holes may be provided in the rods for adjusting the length of the hanger rods and thus adjusting the height at which the dipping frame I5 is carried.

The bottom ends of each pair of hanger rods 31 are detachably swiveled at 39 to the outer ends of longitudinally extending carrier bars 40 which may be channels as shown and which are located at opposite sides of the frame l5, In the center of each bar 40 at its bottom edge a swivel ring 4| is secured as by welding and said swivel rings .are journaled on the ends of rods 42 extending Each dipping frame l5 preferably includesan` `intermediate portion which is xed on the pivot rods 32, and an outer portion which is vertically movable relative thereto. The xed portion preferably includes longitudinally extending angles 44, one at each side of the frame and one extend- The longitudinal angles 44 are supported at their outer ends on transversely extending angles 45 which extend throughout the full width of the frame proper.

A pair of vertical guide tube 46 is secured as by welding to the outer surface of each angle 45, said tubes being preferably spaced laterally inward a slight distance of the outside angles 444 of the frame.

Themovable part of the frame is movably and detachably mounted in these tubes 46 by means of vertical rods 41 which extend slidably through the tubes. Preferably, the rods 41 are provided with screw threads at their top and bottom ends, and longitudinal channel braces 49 connect the top ends of opposite rods 41. preferably the ends of the channels 4e have tubular bosses `il() `welded at their ends, and these bosses are adjustably secured to the top ends of the rods 41 by means of lock nuts 5I. To the bottom ends of the rods 41 transverse angles 52 are connected by means of nuts 53, and a plurality of longitudinal pipes or tubes 54 have their ends welded to the inner legs of the angles 52, said pipes being spaced :at intervals transversely of the frame.

Means for moving the outer part of the frame vertically relative to the fixed intermediate part for binding the channel I6 to maintain its shape, preferably includes a cam rod 55 located midway of the transverse angles 45 and extending par allel thereto. The cam rod 55 is journaled in a plate 56 secured to the middle longitudinal angle lill, and is journaled at its ends in similar plates 55 secured as by welding in the outside angles 44. As shown in Figs. 3 and 5, the cam rod 55 is located between the angles 44 of the fixed portion of the frame and the upper channels 49 of the movable portion. Directly beneath each channel 49 a cam `55a is secured on the rod '55, and the outer surface of the cam 55a is adapted to engage a cam block 5'! welded in the channel 49. Operating handles 58 are attached to the cam rod 55, preferably one just inside of each of the plates 56 in which the ends of the cam rod 55 are journaled.

The article I6 which is shown in this case is a multiple channel material carrying platform, which is placed on the pipes 54 with the legs 60 of the channels running transversely of the frame, and with the deck or platform resting on the pipes `54 and the legs 60 extending upwardly therefrom. The material carrying platform is thus placed or loaded into the frame in inverted position, for a purpose to be hereinafter described.

The means for engaging the article I6 to maintain its contour and shape during the impregnating operation is preferably a form or a series of forms secured to the undersides of the channels 44. As shown in the drawings, the form may consist of a series of pipes or tubes 6| extending transversely of the frame parallel to the legs of the article, and supported by means of straps or the like 62, @3 and k54, which are secured as by welding to the undersides of each of the angles 4d, and to which the pipes Si are welded. As shown the pipes 5l are arranged to include a pair of upper and lower pipes on each side of each of the legs E@ of the article.

Referring to Fig. 3, the cam handle 58 is shown turned through for raising the outer movable part of the frame and engaging the several legs St of the article 55 between the respective pairs of pipes 6i. As the cams 55a are rotated to the position shown in Fig. 3, their engagement with the blocks 51 forces the outer movable part of the frame upwardly and raises the supporting pipes 54 to raise the legs Sii of the article upwardly between the pipes 6i. In the closed position of Fig. 3, the upper pipes engage and bind the upper or outer ends of the legs, and the lower pipes engage and bind the underside of the deck at points adjacent to the legs. In this position the frame is adapted for maintaining the shape and contour of the article H during the impregnating operation, without covering any substantial part of the surface of the article, because the pipes provide for line contacts with the article at spaced points.

By rotating the cam handle 58 through 180 to released position, the weight of the outer part of the frame is allowed to move it downwardly to lower the supporting rods 54 and separate the channel legs 66 from the upper tubes (Si so that the article i@ can be unloaded and replaced.

The operation of gradually inverting the dipping frames as they are withdrawn from the impregnating tank, so as to drain excess impregnating compound from the articles I6, may be accomplished by providing suitable means at the discharge end i2 of the tank for gradually inverting the dipping frames to turn the legs of the articles l5 downwardly as they leave the impregnating bath. Such means may include suitable cam tracks or guides on opposite sides of the tank slidably engaging the studs es projecting from opposite sides of the frame.

Preferably the studs are adjustably mounted vertically by securing their inner ends to vertical angles 'ii which are in turn vertically slidable on angles 'i2 welded to the front ends of the outer angles 45 of the fixed portion of the frame. The angles 'il are adjustable on the angles 12 by means of bolts 'i3 passing through holes in the angles 'il and through slots in the angles 12.

As the inverted dipping frames pass over the exit end I2 of the inipre'gnating tank, they pass immediately into the duct iii which communicates with the hood 29, so that the heated atmosphere enclosed above the impregnating liquid Within the hood 2G continues to circulate around the dipping frames so as to provide` for gradual cooling of the articles held therein.

In the operation of the novel method of the present invention, assuming that the dipping `f-rames indicated 4at |511 in Figs. la and 2a lare ,loaded with laminated corrugated paper articles "t6 to be impregnated., the dipping frames first are moved 4by 'the conveyor Yinto the entrance end 526 -of the duct, and are carried -by the bend .i9 of the conveyor track Athrough the portion 25 of the Aentrance duct. The entrance duct is -lled with the heated atmosphere Icirculating from within the hood 2@ communicating with the entrance duct, so that the articles i6 carried by the dipping frames leb are preheated to drive out entrained Amoisture before reaching the impregnating tank 2t. The dipping frames 15b are of course in their normal position shown -in Fig. 3, so that the articles I6 held in the frames are in inverted position, that is, the legs or flanges extend upwardly.

As .the dipping lframes pass over the downtrack they are lowered gradually into the lmolten impregnating compound contained in tank Hl to .the immersion position shown by the dipping frames la, and are maintained at this level substantially throughout their travel `longitudinally through the impregnating tank. As the articles i6 held by the dipping frames are immersed into the molten impregnating compound, the inverted position of the articles permits the molten compound to ow rapidly into the tubular passages formed by the corrugations, because the open ends of the corrugations are at the upper ends of legs 60. Any trapped air in the corrugations is driven oli with entrained moisture in the form of steam which kbubbles through the molten im- -pregnating compound. Ii the articles i6 are immersed with the legs SB depending downwardly, the trapped air and steam is apt to form bubbles within the corrugations and cause a separation of the plies or laminations at various points in the platform or deck of the article. By immers- VVing the channels le in inverted position, the-danger of forming bubbles resulting in separation of the plies is substantially eliminated and the molten compound flows into and through all of the corrugations so as -to uniformly impregnato `the article.

As soon as the articles i6 are immersed in the molten impregnating compound, the corrugated vpaper lamnations lose practically all of their rigidity and would consequently lose their preformed shape entirely if it were not for the fact that they are held accurately in shape by the pipes Sil lil of the dipping frames.

By engaging both sides of the ends `of thelegs Si) between pairs of the pipes I ,and by engaging the platform or deck of the article at points adjacent to the legs while supporting the deck at intervals on the pipes 5d, the preformed shape of the article is accurately maintained, while at the same time the engagements between thearticle and the pipes are substantially linecontacts so as to allow the impregnating compound to come in contact with substantially all of the surface of the article. By changing slightly the positions of the forming tubes or pipes 6l, the contours of the articlelt can be altered somewhat in shape during the impregnating Operation. Thus, if the angular-ity of the legs .6D is desired to be changed to produce a back-drafted article, this can be done in the impregnating `operation by slightly changing the positions Aof the forming pipes 6I, whereas itis impossible to vform such -a back-drafted article when preform- .ing the laminations to producethe `articles `Hi before they are impregnated.

Wardly inclined portion 13 of the conveyorA As previously stated, the temperature of vthe Y-molten impregnating compound is maintained 'at about 130C. to 140 AC. by suitable vmeans such as steam coils at the ybottom of the tank. The speed of travelof vthe :frames is `correlated to the length 4of vthe `tank so that the articles carried ver-teclas they arerraised-out-of the impregnating liquid, all excess impregnating compound .is thoroughly drained ffrom within `the channels and from within the -corrugations of the :channels. Due to the I:tact `thatthe frames -onileavling ztlie Atank pass ,immediately into the duct ii which communicates with the 4hood 29, the -temperature of the atmosphere inthe duct is only 6 to^8 lower than the temperature of the "ba-th, so -that the solidification of .the irripregnating compound left inthe pores of -the 'article takes place very gradually, which provides suflicient time for the ymolten compound to drain completely from the corrugations. The combined Ylength -of the -duct `V-21 andthe return duct 22 is lcorrelated-with 'the speedoi travel -of-'the frames r,so that the dipping frames are within the duct for about l5 `to 7 minutes-after leaving Mthe -impregnating tank.

the dipping "frames move continuously valong the closed loop of the-conveyor `vtrack, the space-onthercturn run VI8 ofthe track-between the discharge end of the return duct22 and the entrance-end 2B of the entrance duct-L25 Vis avail- `ablefor the operations of manually turning the frames tback to the upright position shown in `Fig. "3, then lreleasing the movable portions dby turning'the ,handles 58 to rotate the cams Y55a andjlower the'bottom pipes 5H of the framestogether Vwith the `articles I6, and then removing the 'impregnated articles and replacing and clamping new preformed articles in -the `frames to b e impregnated.

Accordingly, the present invention provides for carrying out Na novel continuous method of impreenatins lpreformed laminated iflbrOuS larticles.for.strengthening the same, Vwhile maintaining rtheir preformed contours and `dimensions.

In ,the foregoing description, certain terms have been usedfor brevity, clearness and understanding, but yno unnecessary limitations are to rlue .implied therefrom beyond the requirements of the prior art, because such words .are ,used

for descriptivepurposes herein and are intended ,to be broadlyconstrued.

.Havngnow ldescribed `the invention, the construction, the operation and useof a `preferred embodiment .thereof `and .the vvadvantageous new .amd useful` results obtained? thereby; the Vnew land -`theart, are, set forth rin fthe=appended1claims We..claim: ,1. -The1method of .continuously impregnating laminated corrugated paper .channels having transversely extending corrugations forming tubular passages opening at the ends of the channel legs, comprising the steps of holding said channels to maintain their shape, continuously moving said channels in legs-up position into and through a heated impregnating bath, and inverting said held channels as they pass out of said bath.

2. The method of continuously impregnating preformed laminated corrugated paper articles having at least one angular leg and having transversely extending corrugations forming tubular passages opening at the end of the leg, which includes engaging both sides of the leg at its outer end to hold the articles to maintain them in predetermined shape, moving said articles with said leg extending upwardly continuously through a heated impregnating bath, and inverting and draining the articles as they move continuously out of said bath.

DOUGLAS D. ADAMS. KARL ROLLIUS. JOHN D. RISHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. THE METHOD OF CONTINUOUSLY IMPREGNATING LAMINATED CORRUGATED PAPER CHANNELS HAVING TRANSVERSELY EXTENDING CORRUGATIONS FORMING TUBULAR PASSAGES OPENING AT THE ENDS OF THE CHANNEL LEGS, COMPRISING THE STEPS OF HOLDING SAID CHANNELS TO MAINTAIN THEIR SHAPE, CONTINUOUSLY MOVING SAID CHANNELS IN LEGS-UP POSITION INTO AND THROUGH A HEATED IMPREGNATING BATH, AND INVERTING SAID HELD CHANNELS AS THEY PASS OUT OF SAID BATH. 